It's pretty much tailor made for batteries and flywheels. 2 seconds is not feasible for pumped hydro, though it still is impressively fast at less than 30 seconds. It is interesting how all of these technologies have their sweet spots.
It's fascinating how mechanical all of this is.
When stuff goes wrong with dams they really go wrong:
https://en.wikipedia.org/wiki/Sayano-Shushenskaya_power_stat...
Standing inside the turbine hall of one of these you can't help but think of the absolutely insane pressure from a water column typically 100's of meters high and half a meter or more across pushing down on a fairly simple valve. Engineering at its finest. To me the big dams are right up there with spaceflight.